The puzzle on page 15 has been driving me nuts. I think the answer on page 28 is wrong. The answer

Andy, I spent my entire career as a mechanical engineer and I’ve never seen math explained as it was in the Quarterly. I just assumed that my slide rule and I don’t subscribe to “new math” principles. 140 is my number as well. 

Was just looking at it again and it may have been a typo
6+(4+4x10) = 86 would work with parentheses 

From Kap: “ Hey guys didn’t you learn PEMDAS in school?”
Kap taught math for 54 years the answer given is correct!

I tip my hat to the math teacher. In my discipline equations are - let’s call it “over defined” to leave nothing that could be misinterpreted. I do take exception however,  to any expression that has 3 equal signs in it. 

Ok, I get it. Had to look up PEMDAS. It's not how I was taught many years ago. But I guess it shows my decades. Thank You for setting me straight.